arXiv 0812.25262008-12-13hep-ph

连续介质中束缚态的重子-介子散射中的λ（1405）

Lambda(1405) in a baryon-meson scattering with a bound state embedded in the continuum

Sachiko Takeuchi, Kiyotaka Shimizu

备注：: 19 pages, 9 figures
发表信息：: Phys.Rev.C79:045204,2009
DOI：: 10.1103/PhysRevC.79.045204

摘要：

我们研究了耦合道重子-介子散射中的Lambda（1405）共振。这个BSEC是手工引入的，作为一个不起源于简单重子-介子系统的状态。我们假设它来自三夸克态。当N Kbar通道被认为是强吸引时，在低于N Kbar阈值的σ π散射中出现共振。它的出现并没有引入黑海经合组织，就像手征统一办法一样。当引入BSEC时，重子-介子相互作用较弱时也会出现共振。相应的峰也有一个大的宽度，和NKbar散射长度再现良好。通道依赖性与色磁相互作用相同的相互作用，其中不存在N Kbar吸引力，在BSEC的帮助下也给出了类似Lambda（1405）的宽峰。结果表明，在动量转移为零时，BSEC耦合不消失，BSEC耦合的宽度较大。为了重现观测到的N Kbar散射长度，似乎最好采用黑海经合组织。在我们的计算中，当黑海经合组织对共振的贡献大约是N Kbar大小的一半时，模型给出了一个适当的值。

英文摘要：

We investigate Lambda(1405) as a resonance in a coupled channel baryon-meson scattering with a `bound state embedded in the continuum'(BSEC). This BSEC is introduced by hand, as a state not originated from simple baryon-meson systems. We assume it comes from the three-quark state. There appears a resonance in the Sigma pi scattering below the N Kbar threshold when the N Kbar channel is taken to be strongly attractive. It occurs without introducing a BSEC, just like the chiral unitary approach. When a BSEC is introduced, a resonance also appears with a weaker baryon-meson interaction. The corresponding peak also has a large width, and the N Kbar scattering length is reproduced well. The interaction whose channel dependence is the same as the one originated from the color-magnetic interaction, where no N Kbar attraction exists, also gives a broad peak like Lambda(1405) with help of a BSEC. It is found that the BSEC coupling which does not vanish at the zero momentum transfer give a larger width. In order to reproduce the observed N Kbar scattering length, introducing a BSEC seems preferable. In our calculation, a model gives an appropriate value when the BSEC contribution to the resonance is roughly half of that of the N Kbar in size.

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英文摘要：

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